The invention relates to a return stop limiting torque, which is embodied as a latch lock, roller free-wheel, clamp body free-wheel, or the like, particularly for conveyer systems, comprising an internal ring arranged on a drive shaft, an external ring embodied concentrically in reference thereto, and several retaining elements arranged in the annular gap between the internal and the external rings, which allow a relative rotation between the internal and the external rings in one direction, and block it in the other direction in a form-fitting fashion or by way of friction, with the external ring comprising friction-areas at its radially extending faces, which can be axially clamped against corresponding friction disks, with the friction disks being supported in a torque-proof fashion, but at least partially displaceable in the axial direction.
Such a return stop is known from DE 32 45 347 of the same applicant; its content is therefore included in the objective of the present application.
In the following discussion of the objective of the invention, for reasons of simplification, reference is made to a conveyer belt, without this being considered a restriction of the range of application of the invention.
In conveyer belts transporting upwards and using more than one drive pulley the load is evenly distributed over the pulleys during operation. However, when the loaded conveyer is stopped an uneven distribution of load develops when stiff return stops are used. The pulleys and the conveyer belt are unloaded during the run-down process. However, when the load is engaged, the drive pulley with the return stop engaging first is stressed to a greater extent, while the return stops of the other drive pulleys, due to the here developing belt strain, are subject to a considerably lower load. This can lead to excess load and destruction of the drives at the first drive pulley. Accordingly there is a need for a return stop which, when excess torque occurs, distributes said excess torque to the other drives by way of controlled slippage.